At architecture journal bdonline, Wouter Vanstiphout's piece about the planning and related political implications of the riots begins in urban France:

In November 2005 French President Jacques Chirac welcomed back normality, after weeks of riots in the French banlieues. Instead of 1,000 to 1,500 vehicles being burnt every night, it went back to 163, and then kept to the normal 50 to 150. Every night of the year dozens of cars are being set on fire in the French banlieues and this had been going on for years on end.

What is normality to a French banlieue? It can mean that in the morning the elderly, women and children – and sometimes architects and historians looking for modernist housing projects from the sixties – can freely roam between the slabs and blocks, shop, play and look around.

After that the unemployed young men appear from their bedrooms and take up their positions near the entrances of the apartment blocks and on street corners. The elderly, women and children scuttle back home and the tourists leave altogether. The young men whistle and sign to each other, taunt and threaten the belated visitors and the semi-militarised police that buzz by in vans.

In many French banlieues, day turns into night around noon. Once, in one of these places, we approached a group of heavily armed policemen to ask for directions on the central square of a French housing estate.

They looked around nervously and said we shouldn't stand still for too long, because one of the gangs could start throwing rocks. They then said that we should really really be back in the historic city centre within the hour; it was 3pm. They themselves would be out of there at dusk, at the latest. This was between riots, this was normality.

I know of nowhere in London that matches that description, but can we rule such scenarios out of the capital's future? The comparison is inexact: "banlieue" means the urban outskirts, not the inner city areas where our riots began and mostly occurred. However, some fear that the effect of the government's housing and other benefit reforms will be to foster banlieue-type concentrations of social marginalisation in London's poorer suburbs, making the capital's current situation even worse.

Vanstiphout continues:

In many ways, the [French] riots were "just" spectacular worsenings of a chronic condition, extrapolations on a permanent crisis lived by millions, but neglected by tens of millions. Something became visible for a moment, and then disappeared again, as a bad dream. Behind the scenes however a mechanism is in place that contains the badness, that keeps it from spilling over again, while making it inevitable that it will...the banlieues and their inhabitants have been effectively abandoned...

One person did well out of it, though: Nicolas Sarkozy, who as a minister of the interior fanned the flames by going on television, standing shoulder to shoulder with the riot police and calling the rioters scum (racaille) who would be wiped away; then rode the wave of popular fear all the way to the presidency, from where he invited a battalion of international architects to give back France its glory, by designing futures of the French capital, "Le Grand Paris"....

Right now it has become very difficult to think of an urban politics, let alone an urban planning or design approach that would be able to take on the underlying problems of riots like the ones in the UK in a serious way.

I do not think that the reason is that politics and planning have realised their limitations to shape society. I think that the reason is that urban politics and hence planning and urban design are too often treating the city with ulterior motives, instead of actually working for the city itself. The city has become a tool to achieve goals, political, cultural, economic or even environmental [my emphasis].

Treating the city in this way means that we are constantly passing judgment on what the city should be, and who should be there, and what they should be doing, instead of trying to understand what the city actually is, who really lives there and what they are doing. This produces a dangerous process of idealisation, denying whole areas, whole groups, their place in the urban community, because they do not fit the picture.

Something there for politicians of all persuasions to reflect on. And there's more:

It is much too soon to say anything about the relationship between the gentrification of Brixton or the coming of the Olympics to London, and the current explosion of violent alienation. But if we imagine another kind of urban politics, one that does not take into account a marketable image of the city, but the reality of the entire community, it would probably have entirely different priorities.

The first would be to work against the ever sharpening inequality of London, making it one of the unfairest cities in Europe, in poverty levels, education, crime and other indicators.

But then the reality of urban riots is that they have always turned out to be the opposite of a learning experience for a city. Riots have nearly always resulted in politicians simplifying the problem even more, and citizens looking away even further.

After a riot, your average city will become more afraid, more authoritarian, more segregated, more exclusive and less tolerant. That is the real tragedy of the post-war western urban riot, first it shocks and terrifies us, then for a moment it makes us see flashes of the kind of city we should be working towards, which then fades away into the darkness. Back to normal.

A "normal" that is unacceptable.

Wouter Vanstiphout is a partner at Crimson Architectural Historians in Rotterdam and professor of Design & Politics at the Technical University Delft. He is currently researching the relationship between urban riots and urban planning. I'm very grateful to @amarkodio for bringing Vanstiphout's article to my attention.